To face a challenge brought by wireless broadband technologies and keep advantages of a 3rd Generation Partnership Project (3GPP) network, the Long Term Evolution (LTE) project of a mobile communications network is formulated in the 3GPP. Under the direction of the Long Term Evolution project, a new mobile communications network architecture is defined, that is, an architecture of a System Architecture Evolution (SAE) network system.
FIG. 1 is a schematic architectural diagram of a SAE network system in the prior art. As shown in FIG. 1, when user equipment (UE) accesses the SAE network system by using a serving general packet radio system support node (SGSN), the UE may access a serving gateway (SGW) using an S4 interface, and then access a packet data network gateway (PDN-GW or PGW) using an S5 interface. Alternatively, the UE may directly access the PGW using a Gn/Gp interface. Functions of main network elements in the SAE network system are described as follows:
The mobility management entity (MME) is mainly responsible for functions in an evolved universal mobile telecommunications system terrestrial radio access network (E-UTRAN), such as UE mobility management, session management, encryption and integrity protection of non-access stratum (NAS) signaling, temporary identifier allocation for UE, and PGW and SGW selection. The MME corresponds to a control plane part of an SGSN in the Universal Mobile Telecommunications System (UMTS).
The SGW is mainly responsible for relaying a user service flow between the UE and the PGW, and is used as an anchor during handover between base stations.
The PGW is mainly responsible for user address allocation, execution of policy control, execution of a charging rule, and a function related to lawful interception.
The policy and charging rules function (PCRF) entity determines a corresponding policy according to limitations of a user access network, an operator policy, user subscription data, information about a service currently performed by a user, and the like, and provides the policy for a transmission gateway for execution, so as to implement policy charging control.
The home subscriber server (HSS) is responsible for storing user subscription information.
The operator's Internet Protocol (IP) services are implemented in an LTE network by using an IP multimedia subsystem (IMS) network. In addition, a packet switched streaming service (PSS) technology is a technology that is defined in the 3GPP and that is used for providing a streaming media service for the user. A PSS network architecture mainly includes a mobile terminal and a PSS server that is on a network side.
On the basis of the architecture of the SAE network system shown in FIG. 1, to detect a congestion status of a cell in an access network, a radio access network congestion awareness function (RCAF) entity is introduced into the 3GPP. FIG. 2 is a schematic architectural diagram of a SAE network system with an RCAF entity. As shown in FIG. 2, the RCAF entity is connected to a radio access network (RAN) using an operation, administration and maintenance (OAM) system of a RAN, obtains a congestion status of a cell, and requests UE information or access point name (APN) information in the cell by using the MME or the SGSN. Then, the RCAF entity notifies the PCRF entity of a congestion status of a cell in which the UE is located. The architecture shown in FIG. 2 further includes a traffic detection function (TDF) entity and a policy and charging enforcement function (PCEF) entity. The TDF entity is mainly used to detect network traffic. The PCEF entity and the PGW may be integrated into a network device. The PCEF entity is mainly used to execute the policy determined by the PCRF entity.
In the prior art, the PCRF entity formulates a data flow transmission policy only according to information such as an operator policy or user subscription data, and therefore user experience may be poor.